Este trabalho apresenta um estudo experimental do comportamento de juntas transversais em placas de concreto simples, apoiadas sobre fundação elástica. Uma vez sujeita a tensões, provocadas tanto pelo carregamento como por empenamentos e variações volumétricas da placa, as juntas podem provocar uma redução sensível na vida do pavimento, caso não estejam devidamente dimensionadas para suportar as cargas impostas. Devido a isto, a conexão mecânica entre as placas do pavimento é fundamental para garantir uma melhor eficiência na transferência desses esforços e, consequentemente, um aumento na vida útil do pavimento. No trabalho, faixas de concreto, com dimensões de 220 cm x 60 cm e espessuras de 12 cm e 16 cm, foram ensaiadas com força monotônica até a ruína, considerando força em um dos lados da junta. O estudo analisou o comportamento do sistema placa-junta para diferentes dispositivos metálicos de transferência, sendo eles: barras de seções circulares e quadradas, placas e discos, adotando dois dispositivos por modelo ensaiado. Dois diferentes tipos de juntas foram analisados, segundo sua tipologia, como juntas serradas e juntas moldadas. Os resultados experimentais mostram que o aumento na espessura do pavimento aumenta sua capacidade resistente, para os dois tipos de junta. Já a tipologia da junta pode influenciar na força de ruína da peça, uma vez que a presença de concreto abaixo do dispositivo causa variação na rigidez vertical do conjunto, conhecida como interação concreto-barra, levando o modelo serrado a romper com uma carga superior. Os ciclos de carregamento aumentaram a propagação de fissuras sob o lado carregado, reduziram a força de fissuração em parte dos modelos, mas não reduziram sua força de ruína. O disco metálico, em função dos dados coletados, apresentou o melhor desempenho em relação aos demais, e é sugerido como o dispositivo de transferência de carga preferencial para se obter uma maior eficiência do sistema. / This paper presents an experimental study of the behavior of transverse joints in slabs of plain concrete, under elastic support. Once it subjects to tensions, caused so much by the loading as for warped and volumetric variations of the slap, the joints can cause a sensitive reduction in the life of the pavement, in case they are not properly design to support the loads forced. Due to this, the mechanical connection among the slabs of the pavement is fundamental to guarantee a better efficiency in the transfer of those efforts and, consequently, a prolongation in the useful life of the pavement. In the paper, concrete areas, with dimensions of 220 cm x 60 cm and thickness of 12 cm and 16 cm were loading frame monotonic until the rupture, in one on the sides of the joint. The study analyzed the behavior of the system slab/joint for different metallic devices of transfer, being them: dowels of circular and square sections, plates and disks, adopting two devices for model. Two different types of joints were analyzed, according to the typology, as sawed and molded joints. The tests data show that the increase in the thickness of the pavement increases in resistant capacity, for the two types of joints. Already the typology of the joints can influence in the maximum load of the model, once the concrete presence below the device causes variation in the vertical rigidity of the group, known as interaction concrete-dowel, taking the sawed model rupture with a superior load. The loading cycles increased the cracks propagation under the load side, they reduced the load crack partly of the models, but they didn\'t reduce ultimate force. The disk plate, in function of the collected data, presented the best performance in relation to the others, and it is suggested as the preferential transfer device of load to obtain a larger efficiency of the system.

Continuous longitudinal and transverse U-bar joint connections between flanges of the decked bulb-Ts (DBTs) or between precast panels for accelerated bridge construction are investigated. The procedure for selecting durable closure pour (CP) materials for the connections is discussed firstly. The accelerated construction is quantified as two categories: overnight cure and 7-day cure of CP materials. Candidate materials are selected first based on literature review as well as tests of compressive strength and flow and workability. Then, performance criteria for selecting durable CP materials for both categories are developed based on durability tests of selected candidate materials. These durability tests include freezing-and-thawing durability, shrinkage, bond, and permeability tests. To investigate the longitudinal U-bar joint details, four pairs of full-scale slabs connected by a U-bar detail with one of the selected CP materials, overnight cure and 7-day cure, were tested. The loading demand necessary in the slab testing is determined based on the maximum forces in the longitudinal joint from an analytical parametric study. Static and fatigue tests under four-point flexural loading and three-point flexural-shear loading were conducted. Test results were evaluated based on flexural capacity, curvature behavior, cracking, deflection and steel strain. The transverse U-bar joint details are investigated to provide negative moment continuity in the multi-span bridges. Four full-scale specimens connected by a U-bar detail with one of the selected CP materials, overnight cure and 7-day cure, were tested. Static and fatigue tests under tension loading were conducted. The loading demand necessary in the beam testing is determined based on the maximum forces in the transverse joint from an analytical study. Test results were evaluated based on tension capacity, cracking, displacement and steel strain. Based on the test results, the developed longitudinal and transverse U-bar joint details are viable connection systems.

Este trabalho apresenta um estudo experimental do comportamento de juntas transversais em placas de concreto simples, apoiadas sobre fundação elástica. Uma vez sujeita a tensões, provocadas tanto pelo carregamento como por empenamentos e variações volumétricas da placa, as juntas podem provocar uma redução sensível na vida do pavimento, caso não estejam devidamente dimensionadas para suportar as cargas impostas. Devido a isto, a conexão mecânica entre as placas do pavimento é fundamental para garantir uma melhor eficiência na transferência desses esforços e, consequentemente, um aumento na vida útil do pavimento. No trabalho, faixas de concreto, com dimensões de 220 cm x 60 cm e espessuras de 12 cm e 16 cm, foram ensaiadas com força monotônica até a ruína, considerando força em um dos lados da junta. O estudo analisou o comportamento do sistema placa-junta para diferentes dispositivos metálicos de transferência, sendo eles: barras de seções circulares e quadradas, placas e discos, adotando dois dispositivos por modelo ensaiado. Dois diferentes tipos de juntas foram analisados, segundo sua tipologia, como juntas serradas e juntas moldadas. Os resultados experimentais mostram que o aumento na espessura do pavimento aumenta sua capacidade resistente, para os dois tipos de junta. Já a tipologia da junta pode influenciar na força de ruína da peça, uma vez que a presença de concreto abaixo do dispositivo causa variação na rigidez vertical do conjunto, conhecida como interação concreto-barra, levando o modelo serrado a romper com uma carga superior. Os ciclos de carregamento aumentaram a propagação de fissuras sob o lado carregado, reduziram a força de fissuração em parte dos modelos, mas não reduziram sua força de ruína. O disco metálico, em função dos dados coletados, apresentou o melhor desempenho em relação aos demais, e é sugerido como o dispositivo de transferência de carga preferencial para se obter uma maior eficiência do sistema. / This paper presents an experimental study of the behavior of transverse joints in slabs of plain concrete, under elastic support. Once it subjects to tensions, caused so much by the loading as for warped and volumetric variations of the slap, the joints can cause a sensitive reduction in the life of the pavement, in case they are not properly design to support the loads forced. Due to this, the mechanical connection among the slabs of the pavement is fundamental to guarantee a better efficiency in the transfer of those efforts and, consequently, a prolongation in the useful life of the pavement. In the paper, concrete areas, with dimensions of 220 cm x 60 cm and thickness of 12 cm and 16 cm were loading frame monotonic until the rupture, in one on the sides of the joint. The study analyzed the behavior of the system slab/joint for different metallic devices of transfer, being them: dowels of circular and square sections, plates and disks, adopting two devices for model. Two different types of joints were analyzed, according to the typology, as sawed and molded joints. The tests data show that the increase in the thickness of the pavement increases in resistant capacity, for the two types of joints. Already the typology of the joints can influence in the maximum load of the model, once the concrete presence below the device causes variation in the vertical rigidity of the group, known as interaction concrete-dowel, taking the sawed model rupture with a superior load. The loading cycles increased the cracks propagation under the load side, they reduced the load crack partly of the models, but they didn\'t reduce ultimate force. The disk plate, in function of the collected data, presented the best performance in relation to the others, and it is suggested as the preferential transfer device of load to obtain a larger efficiency of the system.

The interstate highway system is vitally dependent upon current and future bridges. These bridges must be designed economically to continue the serviceability with limited maintenance. For precast bridge construction a portion of the design must consider the bridge connections. Some current connections have proved insufficient in serviceability as there is uncontrolled cracking. In other connections there are uncertainties in the calculations (or lack of calculations) which require design guidelines. This thesis presents design recommendations for precast decking u-bar reinforcement in tension which results from negative moment over a pier. Testing results from the University of Tennessee were analyzed to determine the design recommendations. The calculated capacity of the specimens was determined first by strut and tie modeling by AASHTO and ACI, but was shown to be insufficient. Proposed changes to the current calculation of the strut width as specified in AASHTO and ACI STM methods were discussed in order to match the test results. However, strut and tie modeling demonstrated that the design for the lacer bar was inadequate. Since the strut and tie modeling method resulted in an inaccurate lacer bar size, another method was developed. A triangular shape develops from the flow of forces in the connection joint zone; as a result, a free body diagram (FBD) was developed from the concrete triangular shape. This diagram showed how the forces flow in the in-situ joint as well as how they are resisted. A formula was developed from the FBD to determine the capacity of the joint which accurately reflected the capacities from tests. A FBD was also made of the lacer bar utilizing the forces and geometry calculated from the capacity calculations. A computer analysis program was used to determine the forces in the lacer bar. The lacer bar could then be designed since the required forces to resist (moment and shear) were known. A comparison of the strut and tie model to the triangular method led to the conclusion that both can determine the longitudinal reinforcement spacing, joint overlap length, and concrete strength, but only the triangular method can determine a more sufficient lacer bar size.

Made available in DSpace on 2014-07-29T15:03:40Z (GMT). No. of bitstreams: 1 dissertacao juliano rodrigues silva.pdf: 578093 bytes, checksum: c12275364c2b3987c5d82706341b793c (MD5) Previous issue date: 2009-03-12 / This work presents an experimental study of the behavior of transverse joints in unreinforced concrete slabs under elastic support. Due to the tensions caused by loads and volumetric variations in the slab, transverse joints when badly executed can cause a efficiency reduction in the shear transfer, thus reducing the useful life of the concrete pavement. To have a better efficiency in the shear transfer in joints of concrete pavements, 500 mm transfer bars are used with bar diameters varying from 10 mm to 32 mm. These bars are positioned at midheight of the sawed joints spaced at every 300 mm. This research seeks to verify the influence of the positioning of the transfer bars and the influence of different types of concrete on sawed joints of concrete pavements. Three different types of unreinforced concrete were used: conventional concrete, steel fiber concrete and self-compacting concrete. The experimental program consisted of the application of static monotonic loading in nine concrete plates, simulating concrete pavements, with dimensions 2200 mm x 600 mm, with a sawed joint at midlength supported by an elastic rubber layer. The experimental results showed that joints with transfer bars performed much better than those joints without transfer bars and that bars located at midheight perform better than those bars positioned at 45 mm from the base. The concrete types were quite different, however the steel fiber concrete was shown to be more efficient than the other two concrete types, and the conventional concrete was more efficient than self-compacting concrete, probably because aggregate interlock is better in conventional concrete / Este trabalho apresenta um estudo experimental do comportamento de juntas transversais em placas de concreto simples, apoiadas sobre uma fundação elástica. Devido às tensões provocadas pelo carregamento e por variações volumétricas das placas, as juntas transversais quando mal executadas podem ocasionar uma redução da eficiência da transferência de esforços, reduzindo assim, a vida útil do pavimento de concreto. Para que ocorra uma melhor eficiência da transferência dos esforços nas juntas transversais são utilizadas barras de transferência com diâmetro comercial variando de 10 mm a 32 mm e comprimento de 500 mm. Essas barras são posicionadas sob as juntas serradas na altura de ½ da espessura da placa de concreto e posicionadas a cada 300 mm uma da outra. Esta pesquisa visa verificar a influência das juntas serradas em função do posicionamento das barras de transferência e a influência do uso de concreto simples autoadensável, concreto simples convencional e concreto convencional simples com fibras de aço. O programa experimental constou de ensaios com aplicação de carregamento estático monotônico em nove placas, simulando pavimentos de concreto, com dimensões 2200 mm x 600 mm, dotadas de junta transversal serrada e apoiadas sobre uma camada de borracha. Os ensaios experimentais mostraram que a junta serrada em placas com a presença de barras de transferência tem um desempenho muito melhor do que as placas sem barra de transferência, e que quanto à altura das barras em relação à base, tiveram um melhor desempenho nas barras posicionadas a ½ altura que a 45 mm da base. Os tipos de concreto foram bastante distintos, porém o concreto convencional com fibras se mostrou mais eficiente que os outros dois tipos de concreto, e o concreto convencional se mostrou mais eficiente que o concreto autoadensável, provavelmente em função do intertravamento dos agregados do concreto convencional que são mais solicitados do que os agregados do concreto autoadensável